1. Field of the Invention
The invention relates generally to an intervertebral spacer and method for spacing and fusing adjacent vertebrae and, more particularly, to a porous, strong, intervertebral spacer formed of a biologically inert material.
2. Description of the Prior Art
Techniques and devices for fusing two or more vertebrae of the spine together are well known. Such techniques are commonly performed to correct problems, such as chronic back pain, which result from degenerated intervertebral discs. One technique for fusing together two or more vertebrae of the lumbar spine includes excising a portion of the disc extending between adjacent vertebrae and grafting one or more portions of bone of a desired shape, known as an intervertebral spacer, between the adjacent vertebrae. The intervertebral spacer may be inserted by either an anterior or posterior approach to the spinal column depending on a number of factors, including the number of vertebrae to be fused and past operative procedures. Upon healing, the vertebrae are desirably fused together through the intervertebral spacer.
Conventionally, intervertebral spacers have been autogenic bone harvested from other areas of the body, such as the pelvis, allogenic bone taken from cadavers or xenogenic bone, such as bovine bone sections. However, the use of bone grafts can add complications to the fusion procedure. For example, when using an autogenic bone graft, a second incision must be made in the patient to harvest the additional bone to be used in the graft, thus increasing the pain and blood loss to the patient. When allogenic or xenogenic bone grafts are used there is a potential for the transmission of disease from the cadaver or other graft source to the patient.
The use of non-biological implants, such as carbon fiber spacers, also has been attempted in the past, but these spacers tend to lack sufficient porosity and tissue ingrowth characteristics to function adequately.
It would be desirable to provide a non-biological spacer which is non-reactive in the body and which has the strength and tissue ingrowth characteristics of a bone graft spacer.